<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        let arr = [2,4,6]
        console.log(typeof arr);
        console.log(typeof {});

        console.log(Array.isArray(arr));//true
        console.log(Array.isArray({}));//false
    </script>
    <script>
        console.log("==伪数组===");
        console.log([1,3,5]);

        var arr_ = {
            0:'aa',
            1:55,
            2:77,
            length:3
        }
        console.log(arr_);

        var arr2 = Array.from(arr_)
        console.log(arr2);
    </script>
    <script>
        var scoreArr = [77,66,23,88];
        //循环
        var index = scoreArr.findIndex(function(item){
            console.log(item);
            if(item<60){
                return true;
            }
        })
        console.log('index',index);

        console.log('==不及格成绩==');
        //el
        var score = scoreArr.find(el=>el<60);
        console.log('score',score);
    </script>
    <script>
        console.log("==过滤===");
        let ageArr = [23,77,33,88];
        let newArr = ageArr.filter(el=>el>60);
        console.log(newArr);
    </script>
</body>
</html>